Wherefore it behoved him — It was highly fit and proper, yea, necessary, in order to his design of redeeming them. To be made in all things — That essentially pertain to human nature, and in all sufferings and temptations. Like his brethren — This is a recapitulation of all that goes before: the sum of all that follows is added immediately. That he might be a merciful and faithful High Priest — Merciful toward sinners; faithful toward God. A priest or high priest is one who has a right of approaching God, and of bringing others to him.
Faithful is treated of, Hebrews 3:2, &c., with its use; merciful, Hebrews 4:14, &c., with the use also; High Priest, Hebrews 5:4, &c., Hebrews 7:1, &c. The use is added from Hebrews 10:19.
In things pertaining to God, to expiate the sins of the people — Offering up their sacrifices and prayers to God; deriving God's grace, peace, and blessings upon them.